1. Field of the Invention
The present invention is directed to a fuel system for an internal combustion engine and, more particularly, to a fuel system having means for switching from a recalculating system in which unused fuel is returned to the fuel tank to a non-recalculating, dead-headed system which avoids fuel return and consequential fuel tank warming.
2. Description of the Relevant Art
Fuel injected internal combustion engines are employed as an alternative to conventional carburated engines. Such systems provide a more accurate means, as compared with carburated engines, to control a variety of engine operating parameters via an on-board electronic control module (ECM).
Fuel is typically supplied to a fuel injected engine via a fuel distributor which is operably connected to a series of fuel injectors. The injectors are mated to an engine intake in such a manner that they are positioned within respective intake ports of the engine. Pressurized fuel from one or more fuel pumps, which draw fuel from a supply, is circulated to the fuel distributors where it is dispensed by the injectors. In many cases, excess supplied fuel is recirculated to the fuel tank by a pressure relief valve which maintains correct fuel pressure within the fuel distributor. Recirculation of fuel is, in most cases, only required during operating periods when fuel vapor is a possibility in the fuel distributor. Otherwise, the effect of recirculation is to return fuel, which has been heated by passage through the engine bay, to the fuel tank causing an increase in tank fuel temperature and vehicle emission running losses.